Distributed control systems (DCS) are a new generation of instrument control systems based on microprocessors, employing the design principles of decentralized control functions, centralized display and operation, and a balance between decentralized autonomy and comprehensive coordination. DCS can also be translated as "distributed control system" or "distributed computer control system."
A distributed control system, also known as a distributed overall control system, is a decentralized direct control device with a microprocessor as its core. Its control functions are distributed (with subsystems centered around the microprocessor), while management is centralized (using a computer). Compared to a centralized control system, it has the following characteristics:
1. High reliability (i.e., risk dispersion). Microcomputers with microprocessors at their core are more reliable than small and medium-sized computers. Even if a part of the system fails, it will not affect the whole system. When the management computer fails, each subsystem can still be controlled independently.
2. The system has a reasonable structure (i.e., a decentralized structure). The system's input and output data are pre-processed or selected by subsystems, reducing the amount of data transmission, alleviating the load on the microcomputer, and improving the control speed.
3. Due to the reduced amount of information, programming is simpler, and modifications and changes are very convenient.
4. Due to the decentralized control functions, the reliability of the subsystems is improved, and the requirements for the management computer and the microcomputer can be reduced.
DCS typically adopts a hierarchical structure, with each level consisting of several subsystems. Each subsystem achieves several specific and finite objectives, forming a pyramid structure.
Reliability is the lifeblood of DCS development. To ensure high reliability in DCS, three main measures are taken: first, the widespread application of highly reliable hardware and manufacturing processes; second, the extensive adoption of redundancy technology; and third, the widespread implementation of fault-tolerant technology, fault self-diagnosis, and automatic processing technology in software design. Today, most distributed control systems can achieve a MTBF (Mean Time Between Failures) of tens of thousands or even hundreds of thousands of hours.
Distributed control systems (DCS) are designed with the basic principles of decentralized control and centralized operation and management, employing a multi-level, hierarchical, cooperative, and autonomous structure. Their main characteristics are centralized management and decentralized control. Currently, DCS is widely used in various industries such as power, metallurgy, and petrochemicals.
